1. Field of the Invention
The present invention relates to irrigation systems and to trickle or drip irrigation units for dispensing water and other liquids with or without fertilizers for the nourishment of plants and other vegetation below, on and above the ground.
2. Information Disclosure Statement
By way of background, U.S. Pat. No. 3,420,064, by Blass et al., issued Jan. 7, 1969, discloses an irrigation dripper unit containing a continuous elongated helical groove for deriving water in small quantities from a main stream. U.S. Pat. No. 3,604,728, by Blass et al., issued Sept. 14, 1971, also discloses a continuous elongated helical groove in an irrigation dripper unit.
An irrigation device effecting drip action of water from a central tube was disclosed in U.S. Pat. No. 3,667,685, by Isaac Rinkewich, issued June 6, 1972. The flow path of the water in that device is labyrinthine so that the water path continuously reverses in order to create substantial turbulence to maintain in suspension the foreign matter to minimize the likelihood of clogging.
Another dripper for irrigation was disclosed in U.S. Pat. No. 3,729,142, by Rangel-Garza et al., issued Apr. 24, 1973. That irrigation dripper comprises a substantially cylindrical hollow thin walled female member having an open receptacle end and a smooth interior wall surface, a male member for insertion into the female member having ridges on its outher surface for engaging said interior wall and providing between the wall and the valleys between the ridges of the male member a meandering zig-zag liquid low path and discharge means for the liquids between the male and female members thereby providing with the female and male members a liquid dispensing head. That dripper is proposed as an on-line dripper.
Other flow-reducing devices are apparent from U.S. Pat. No. 3,791,587, by Mordeki Drori, issued Feb. 12, 1974, which discloses also a disc-shaped flow retaining member between disc-shaped annular walls of a drip irrigator.
The subsequent U.S. Pat. No. 3,792,588, by Yigal Gilaad, issued Feb. 19, 1974, for a trickle irrigation unit comprising a pair of telescopic members, of which one is formed with a continuous groove forming with the other member a large cross-section flow path having continuous direction-changing bends.
Drippers of the latter type may be referred to as "in-line drippers", since they have two opposite liquid ports for connecting such drippers into one continuous line.
U.S. Pat. No. 3,815,636, by Stanley W.O. Menzel, issued June 11, 1974, disclosed use of an elastomeric member for drip feed pressure control in devices that may be used in-line or on-line.
In this respect, an "on-line" dripper usually has only one liquid input port for connection to a supply line, as shown, for instance, in U.S. Pat. No. 3,834,628, by Herzl Selman, issued Sept. 10, 1974, for trickle irrigation devices comprising an outer housing and an inner core. The contacting surfaces of the housing and core define a chamber and a plurality of separate parallel labyrinths each communicating with the chamber. The core is fixed within the housing by means of threads which define a spirally-extending conduit providing a path, between the water inlet and the chamber to the labyrinths. In one described embodiment, the core is a unitary member formed with both the threads and the labyrinth configuration; and in a second described embodiment the core comprises two sections, one being formed with the threads, and the other being a replaceable annular insert formed with the labyrinth configuration.
In another on-line dripper, interconnected mating housing halves have a disc sandwiched therebetween and carrying a labyrinthine path in the form of two series-connected circular turns distributed over the two major sides thereof. One of these housing halves has the liquid input port integral therewith, while the dripper output is integral with the other housing half. The disc may include a flexible diaphragm acting on an inward projection of the dripper output to alleviate the effect of excessive water pressure.
An anti-clogging drip irrigation valve is disclosed in U.S. Pat. No. 3,896,999, by Jaime S. Barragan, issued July 29, 1975. A button drip feed device for on-line use is disclosed in U.S. Pat. No. 3,882,892, by S.W.O. Menzel, issued May 13, 1975. Another trickle irrigation emitter is disclosed in U.S. Pat. No. 3,887,139, by D.N. Pearce, issued June 3, 1975.
There is a multiplex dripper assembly for sprinkler risers which contains six independent pressure compensating drippers in a single housing having a common input connected to the sprinkler riser. Each dripper has its own tubular dripper output. Six dripper hoses may thus be served by that muliplex dripper assembly.
There further is an in-line dripper in which a cylindrical male member has series of interconnected labyrinthine paths extending along sections of the cylindrical surface in parallel planes extending at right angles to the longitudinal in-line axis of the dripper. The also cylindrical female member closes these labyrinthine paths circumferentially, and the male member has a radial slot forming the dripper outlet at the female member.
Reference may also be had to U.S. Pat. Nos. 4,392,616, issued July 12, 1983 for Self-Perforating Drip Irrigation Device, and 4,460,129, issued July 17, 1984 for Turbulent Flow Emitter, to Donald O. Olson, and to U.S. Pat. No. 4,589,595 by Glenn G. Havens, issued May 20, 1986 for Pressure Compensated Emitter.